Re: x-ray shielding

[tdc@ehssun.lbl.gov]

>I have a 150 kvp device which is used for ion implantation.  The device
>emits x-rays in bursts during the warm up to the operating potential.

>In order to protect the other individuals in the room ( a large bay area
>housing other equipment for experimental research) I am considering using
>the 100 mrem/yr limit to determine the thickness of lead to place around
>the device - instead of the 100 mrem/wk for the occupational worker.

X-ray shielding is cheap and therefore it is cost effective to be
conservative (I would suspect that 1/8 inch lead would be FAR more than
enough!).  Also I am assuming the work being done at the "other" equipment
is not related to the x-ray use.  If that is the case I would not consider
those persons occupational workers in regards to the shielding of that ion
implanter.

So - I'd go for the 100 mREM/yr and also consider alternative materials
like steel.

I'd like to NOT see this get into a discussion of "no risk below 5 REM/yr".

In an occupational environment there are other "risks".  Especially dealing
with employee "unrest" from non-involved but exposed persons.  In my
opinion it is MUCH cheaper to shield conservatively than the manpower it
would cost to desensitize surrounding workers and deal with this issue when
it resurfaces every few years - as it will!  It also seems to generate some
good will.

I think as long as the enhanced sensitivity to rad issues exists - right or
wrong - this is the cost effective approach.

Ted de Castro
tdc@ehssun.lbl.gov
University of California Lawrence Berkeley Laboratory
Bldg 90 Rm 0026B
Berkeley, CA 94720
(510) 486-5256
(510) 486-6939 - FAX